Wireless selective signaling system.



PATENTEI) JAN. 3, 1903.

C. D. EHEET.

4 WIRELESS SELECTIVE SIGNALING SYSTEM.

APPLIGATION FILED JULY 3 1902.

v mvcm foz 2 SHEETS-SHEET PATENTED JAN 6, 190&

. 0; D. EHVRET. WIRELESS SELBQTIVB SIGNALING SYSTEM- APPLIGATION FILED JULY 3,1902v SIKEE PS-SHEET 2.

J0 MODEL v awuavlfoz v imam Sterne coRNE'LiUs DQEHRE'i, oF RosEMoNT, PENNSYLVANIA.

PATENT tries;

WIRELESS setecr ve SIGNALING svs' r siti.

SPECIFICATION forming part cf Letters Patent-No. 717,978, dated January 6, 1903.

Application filed ui fa, 1902.-

. frequency isg'enerated and modified at the signals.

transmitting-stationandwhi'ch is transmitted throughthe natural media and is received in circuits at the receiving-stations,which; are so proportioned as to their electrical. constants as to respond to such energy of a definite frequency to the-exclusion of other en-. ergies. l a

It further refers to a method of generating in a predetermined order of succession ener-- gies of different frequencies'aud putting the receiving device into. comin-rrnic'ation with s'uch energy in a predetermined manner, so as to select the transmitted energies to the exclusion of other energies an'dih ,the same order as transmitted. V .7 It comprises, further,- a method of cyclically generating different freiquenciesand cyclically receiving different frequenciesrte reproduce a signal, and, furthermore, to cyclically produce a plurality of frequencies simultaneouslyand to receive in the same order a plurality of frequencies simultaneously, which operate conjointly to reproduce a signal or which operate separately to produce separate It hasheretofore been suggested thatelec tiinedf'iisfto its electricai constants so as to rece'i vethat ,2 rgy only and to the exclusion of all'oth'e-rs whereby secrecy of communication could be ohtained. it is possible, how. ever, with such system for an undesired party to read the messages transmitted, for it is only necessary for him to gradually vary the con! stants of his receiving system until they'are such as to se'iect the energy being transmitted. This would require in many instances but a Serial No. H4469. (No model.)

the so-called selective system non-secret. By the method and apparatus her-ein' deenergy representing a signal is changingcyc- Iically and at regular intervalsand that the receiving device is changedas to its electrical .-acter energiesof several f reqnencies are transmitted and received, and in consequence any one trying'to. adjust a simple receiving device toLinte'rrupt such message wouldfail, be-

cause he could adjust to not more than one of such frequencies, and in consequence, due to the relatively slow operation of the appa would mean nothing whatsoever. By the fore, it isapparen'tthat th-epossibility of secret communication is greatly enhanced and the probability of undesired parties reading the message is great ly reduced.

Reference is to be had to the accompanying zdrawingsfin which-e 'Figi'ire l is a diagrammatic view of a transmitting-station for transmitting energies of four different frequencies in a certain order of succession and I in which the inductance conductor except for one-quarter of the time.

adapted to cooperate with the transmitter shown in Fig. 1. Fig. 3 is'a modified form of circuit arrangement for a'transmitter. Fig. 4 is a diagrammatic view of a receiver adapted to-cotiperate with the transmitter shown in Fig. 3. Fig. 5 is a diagrammatic view of a modified form of transmitter. Fig. 6 is a diagram m'a'tic view of. a modified form of a trans- "mitte'rinwhich the'frequencyof the radiated ineans of changing the capacities in an oscillating circuit. Fig. .7 is a modified form of transmitter in whiclutwo energies of 'diderent frequencies are simultaneously radiated and from moment to moment the frequency. of

scribed it is seen that the frequency of theconstants simultaneously and in the same ormethod and apparatus herein described,there'- Fig. 2 is'a diagrammatic view of a receiver energy is changed from instant to instant by Y 'few moments trial and would then render ratus, 'he'vvould receive a Series of dots which each of the energies is changed. Fig. 8 is a diagrammatic view of a modified form of transmitter in which a plurality of energies are simultaneously radiated and of different frequencies and such energies changed'as to their frequency from moment to moment. Fig. 9 is the receiving device to cooperate with the circuit shown in Fig. 8, in which two energies of different frequency are simultaneously received to conjointly produce a signal. Fig. 10 is a diagrammatic view ofa transmitter by which two messages are simultaneously sent from the same aerial conductor and the energy representing each message is cyclically changed'as to its frequency. Fig.-

. in Fig. 10, by which two messages are simultuneously received. Fig. 12 is a modified form of receiver by which two messages are simultaneouslyreceived.

In Fig. 1, A is the usual aerial conductor of a wireless signaling system. At its lower end it is in electrical communication with the trailer 1, which is driven by means not shown at a comparatively slow rate over four segments of the sunflower B. 2, 3, 4, and 5 are the inductances of different magnitudes, which connect at their upper ends to the segments of the sun flower B and at their lower ends with corresponding segments of the sunflower B, over which is driven at the samesaid aerial conductor serves to determine the frequency of the energy radiated from.the aerial conductor-A during the time that the trailers 1 and 6 are passing over the segments to which said inductance 3 is connected. Supposing the trailers 1 and 6 to be rotating in a clockwise direction, the inductance 3 is after a time entirely out of circuit, and the inductance 2 is brought into circuit, thereby causing energy of dilferent frequency to be radiated. from the aerial conductor A. In the same manner the remaining inductances 5 and 4 are brought successively into circuit, and there results, therefore, a radia tion of energy of four different frequencies for each revolution of the trailers 1 and 6. In shunt to the spark-gap S is the usual secondary of a transformer or induction-coil, in whose primary isthe usual Morse key to control the energy according to a telegraphic code. The rate of rotation of the trailers 1 and 6 and also those in the figures hereinafter to be described is such that for the longest code character an entire revolution must be made. It results from this that; an undesired party adjusting his receiving device so as to select any one of the frequencies radiated from the aerial conductor A, which receives an impulse only once in a revolution and so, therefore, receives nothing but a series of dots. p

In Fig. 2 is shown the receiving device adapted to coiiperate with the transmitter shown in Fig. 1. Like reference characters refer to like parts. To the trailer 1 is connected the conductor, 7, which leads through the small condenser k =.o the wave-responsive device 8, thence through the small condenser is to the trailer 6. Trailer 6 is also connected to earth-plate E.' It is apparent, therefore, that the wave-responsive device is in shunt at every instant to one or other of the inductances 2, 3, 4, and 5 and is subjected toa very great potential difference. In shunt to the waveresponsive device 8 is the usual relay 9, whose tongue 10 controls the local circuit, as is well understood in this art. The source ofenergy 11 is connected between the coils of the relay 9, which coils operate then as the usual choke-coils. The object of ihe condensers k k is to prevent the flow of en: ergy from source 11 .through any of the inductances 2, 3, 4, or 5, which were it to occur would keep the relay 9 constantly energized and no signals could be received. The trailers 1 and 6rev01ve synchronously at the transmitting and receiving station, and in consequence when inductance 2 is in circuit at the transmitter inductance 2 is in circuit at the-receiver; and the receiver is therefore at every instant selective of the energy transmitted.

In practice the sunflowers B B should not be flat; but the several segments would be arranged similarly to the teeth of the ratchet, in which case the trailers 1 and 6 would be brushes which would snap quickly from one segment to the other, and the synchronous rotation of the trailers or sunflowers at each of the stations may be procured by rotating them on an arbor 0! a. chronome ter or by a chronometer which at certain intervals closes the circuit to control the speed of rotation, and to adjust to exact synchronism the brushes -or trailers 1 or 6 can be slightly changed in their angular position. i

In Fig. 3 buta single sunflower is employed, and greater portions of the inductance-winding are cut into the circuit'of the aerial conductor A. Portion 12 of the, inductance is always in circuit, and when trailer 13 of the sunflower B isin the position shown the inductance 12 only is in circuit. As it moves in acounter-clockwise direction onto the next contact the portions 12 and 14 are both in circuit with the aerial conductor. On the next contact portions 12,14, and 15 arein circuit and on the next contact portions 12, 14, 15, and 16 are in circuit. S is the sparkgap, as described in connection with Fig. 1, whose one terminal connects to the trailer 13 and whose other terminal connects to the earthplate E. It is seen, therefore, that there are cyclically radiated energies of different frequencies, according as the different o of the receiver are arranged symmetrically with those of the transmitter, and in consequence at each instant there are received two energies of different frequencies, which then control the wave-responsive devices 58, resulting in the simultaneous control of the relays 56 and 59. This results in the tongues 57 and G0 cooperating with their contacts and close the circuit embracing the source of energy 63 and the recording-relay 64, whose tongue 65 controls the final recording-circuit. From moment to moment, however, the energies received change their frequencies; but

at all times two energies are being received which diflferin frequency. This arrangement insures great privacy because of the great difljcult'y encountered by any one attempting to adjust his apparatus to rec ive a message.

In Fig. 10, 66 and 67 are alternator-s or other source of alternating or pulsa'tory currents, which are controlled by keys 68 and 69, respectiVely of the primaries 7O 71,1espectively. 72 is the secondary of the primary 71 and connects to the spark-gap S, whose one terminal connects to earth-plate E and whose other terminal connects to trailer 73, which revolve.- over the segments of the sunflower B, thereby short-oiruiting more or less of the inductance 74, of which there is always a section in circuit. 75 is a secondary of the transformer 70 and is bridged to spark-gap S, one terminal of which connects to the earth-plate E and whose other terminal connects to trailer 76, moving over the segments of the sunflower. B, thereby short-circuiting more orless of the inductance 77, of which the upper portion is always in circuit. By this means two simultaneous messages may be simultaneously transmitted through the aerial conductor A, each one represented by energy of -a different frequency and each energy changing in its frequency from moment to moment, according to the position of the trailers 73 and 76.

In Fig. 11 is shown the receiver adapted to operate in connection with the transmitter shown in 'Fig.'10, in which like characters refer to similar parts in Fig. 10. In series between the aerial conductor andinductauces 7 4 is a wave-responsive device 78, in shunt to which is the relay 79, energized by the source of energy 80, and whose tongue 81 controls the record lug-circuit. In series with inductance 77 and the aerial conductor A is the wavea'e sponsive device 82,-in shunt to which is therelay S3, energized by the source of energy 84, and whose tongue 85 controls the recording-circuit. By this means two independent messages are simultaneously received on the aerial conductor and selected to their proper recording-circuits, and at the same time the constants of each of these circuits upon which its selectivity jdepends change from moment to moment.

In Fig; 12 is shown a modified arrangement of receiver for receiving simultaneously from the small aerial conductor A two independminal connects to earth-plate E.

out messages. In this case inductance 86 is common to both sunflowers B B, butditferent amounts are tapped off tothe segments of each sunflower over which move the trailers 87 and 88. From the trailer 88 is a connection to the primary 89, whose remaining terminal connects to earth-plate E. 90 is the secondary of such transformer, which connects through the small condensers 7a with the wave-responsive device 91, in shunt to which is the relay 92, energized by battery 93, and whose tongue 94 controls a recording-circuit. From the trailer 87 there is a connection to the primary 95, whose remaining ter- 96 is the secondary of such transformer, whose terminals connect to the small condensers k to the terminals of the wave-responsive device 97', in shuntto which there is relay 98, energized by battery 99, and whose tongue 100 controls the local recording-circuit. The functions oi the small condensers k k are to prevent a flow of current from 93 and 09 through the secondaries 90 and 96, respectively. By thearrangement herein shown there may be received simultaneously two energiesof dilferent frequencies, which energies change their frequency from moment to moment. The trailers 87 and 88 rotate synchronously with the trailers at the transmitting devices,such' proper moment.

From the arrangement of apparatus and of the circuits herein des'cribeditis apparent that greater secrecy may be obtained than in the usual simple selective system, for the reason that an undesired party would be unable to adjust his device so as to be selective of more than one frequency.

In the system herein described tuning is resorted to; but it is characteristic that the rate is changed from time to time in a-certain cycle of operations, and, furthermore, in some of the arrangements shown a plurality oE'energies of dilferent characteristicsoperating simultaneously are necessary to produce a signal. It follows, therefore, that the probability of an undesired party interrupting a IIC message is extremely remote, due to' the great nu mber of dependent circu mstances,the prob- .abilitybecoming' very small due to such fact.

That I claim is 1. The method of transmitting intelligence, which consists in emitting in a predetermined orderof succession, energies differing in properties, and subjecting a wave-responsivedevice at the receiver to said energies in an order of succession corresponding withthe order of succession of their emission.

2. The method of transmitting intelligence,

which consists in emitting energies, representing a message, in a predetermined order of successiom'aud simultaneouslysubjecting a wave-responsive device at the receiver to said energies in the same order of succession.

3. The method of transmittingintelligence, which consists in generating and emitting electroradiant energy representing a signal or message, cyclically varying a characteristic wave-responsive device 'at the receiving-station to the cyclically-varying effects of said energy.

6. The method oftransmittingintelligence,

f whichconsistsin generatingelectricalenergy,

cyclically varying the frequency of said energy, and simultaneously subjecting a Waveresponshfe device to the cyclically-varying eii'ects-ofthe varying frequency of the transmitted energy. V

7. The method of transmitting intelligence, which consists in generating electroradiant energy, varying a characteristic of said energy in aseries of steps in a predetermined order of succession, and simultaneously subjecting a wave-responsive device at the receiver to the eifects of the received energy in the same order of succession.

8. The method of transmittingintelligence, which consists in generatingelectrical-energy, cyclically varying a characteristic of said energy, and simultaneously subjecting a waveresponsive device at the receiver to the cyclically-varying effects of said energy in a plurality of circuits selective of the different effects of said energy.

9. The method oftransmitting intelligence, which consists in generating electrical energy,

I I controlling said energy to represent a signal or message, cyclically varying a characteristic -"of said energy, and cyclically bringing a waveresponsive device at the receiver into the infiuence of a plurality of circuits, each circuit being selective of the effects of the transmitted energy when having a predetermined characteristic.

,i 10. The method of transmitting 1minbeing selective of and producing the maxi-' mum effects of the transmitted energy when having a predetermined characteristic. 11. The method of transmitting intelligence, which consists in generating electrical energy, controlling said energy to represent a signal. or message, cyclically varying the frequency of said energy,-and cyclically bringing a translating device at the receiver into the influence of a plurality of circuits, each circuit being selective of the effects of the transmitted energy when having a predetermined frequency.

12. The method of. transmitting intellige'nce, which consists in generating electrical energy, cyclically varying the frequency of said energy, controlling said energy to representa signal or message, and cyclically bringing the translating device at the receiver into the influence of a plurality of circuits, each circuit being selective of and manifesting the.

maximum effects of the transmitted energy when having a predetermined frequency.

13. The method of transmitting intelligence, which consists in simultaneously generating a plurality of electrical energies, controlling said energies to represent a signal or message, cyclically varying a characteristic of each of said energies, and cyclicallybringing a plurality of'wave-responsive devices at thereceiver into the influence of a plurality of sets of circuits, each circuit of a set being selective of the effects of a transmitted energy when having a predetermined characteristic.

14. The method of transmitting intellireceiver into the influence of a plurality ofsets of circuits, each circuit of a set being selective of the effects of a transmitted energywhen having a predetermined frequency, and said translating devices operating conjointly to produce a signal or message.

15. The method of transmitting intelligence, which consists in emitting energy representing a signal or message, cyclically varying a characteristic of said energy, the duration of a cycle being equal to the duration of the shortest element of the signal, and subjecting a wave-responsive device at the receiver to the elfect of the received energy.

. 16. The method of transmitting intelligenes, which consists in generating energy,

varying a characteristic of said energy through predetermined values during an interval of time equal to the duration of the shortest code character, repeating the variation cyclically, and simultaneousl} subjecting a wave-responsive device at the receiver to the cyclically-varying effects of said energy.

' COPNELIUS D. EHRET.

Witnesses: I

Amos T. BU RQUGH, MAE HOFMANN. 

